#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int max3(a, b, c)
{
	int arr[3] = { a,b,c};
	int max = 0;
	int i = 0;
	for (i = 0; i < 3; i++)
	{
		if (max < arr[i])
		{
			max = arr[i];
		}
	}
	return max;
}
int main()
{
	double m = 0;
	int a, b, c;
	scanf("%d %d %d", &a, &b, &c);
	int x1 = max3(a + b, b, c);
	int x2 = max3(a, b + c, c);
	int x3 = max3(a, b, b + c);
	m = x1*1.0 / (x2 + x3);
	printf("%.2lf", m);
	return 0;
}